Engineering Commons^™

Optimizing Irrigation Management For Pollution Control And Sustainable Crop Yield, Ghassan R. Musharrafieh, Richard C. Peralta, Ronald J. Hanks, Lynn M. Dudley

Civil and Environmental Engineering Faculty Publications

Irrigation strategies which maximize crop yield while maintaining target salt concentration in the root zone and/or prevent salt from leaching to the groundwater are computed using a nonlinear, one dimensional, simulation/optimization management model. The included constraint equations maintain a water volume balance and salt transport in the unsaturated zone. Utilized are implicit finite difference forms of the nonlinear, unsteady, unsaturated water flow equation (Richards's equation), and the diffusion-convection solute transport equation. Other constraints include nonlinear functions describing the hydraulic properties of the medium (hydraulic conductivity as a function of matric potential, volumetric water content as a function of matric potential, …

Determination Of Aashto Layer Coefficients For Granular Materials By Use Of Resilient Modulus, David Newton Richardson

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The layer coefficients a₂ or a₃ for an unbound granular base or subbase material are found from a relationship with resilient modulus, E_b. The resilient modulus for a given material can be found by test using the "theta model" or by use of an estimation regression equation. E_b is a function of several factors, as discussed below.

Impact Of Field-Dependent Electronic Trapping Across Coulomb Repulsive Potentials On Low Frequency Charge Oscillations, R. P. Joshi, K. H. Schoenbach, P. K. Raha

Bioelectrics Publications

We have performed Monte Carlo simulations to obtain the field dependence of electronic trapping across repulsive potentials in GaAs. Such repulsive centers are associated with deep level impurities having multiply charged states. Our results reveal a field‐dependent maxima in the electronic capture coefficient, and the overall shape is seen to depend on the background electron density due to the effects of screening. Based on the Monte Carlo calculations, we have examined the stability of compensated semiconductors containing such repulsive centers. Our analysis indicates a potential for low frequency charge oscillations which is in keeping with available experimental data.

An Evaluation Of The Strategic Highway Research Project Packing Handbook, Kenneth P. Cox, Charles F. Scholer, Menashi D. Cohen

JTRP Technical Reports

The objective of this research is to evaluate the use of the November 8, 1991 SHRP C-206 report entitled, “Packing Handbook – A Guide to the Optimal Gradation of Concrete Aggregates”. The purpose of the Packing Handbook is to determine the optimal combination of fine and coarse aggregates for concrete from available aggregate sources. Through the use of tables provided in the Packing Handbook, and given sources with known aggregate gradations and void contents, the relative proportion of each aggregate (coarse and fine) is obtained. Concretes made using the Packing Handbook recommendations of aggregate proportioning were compared to concretes used …

The Impact Of Coal Pyrolysis On Combustion, Peter R. Solomon, Thomas H. Fletcher

Faculty Publications

The pyrolysis process has impacts throughout coal combustion. The roles of pyrolysis in various aspectsof the coal combustion process are described, including the devolatilization yield, nitrogen release, softening and swelling, soot formation, and char reactivity. These processes can be understood and quantitatively predicted using recently developed network pyrolysis models that describe the transformation of the coal's chemical structure. The models are described and examples of their predictive ability for important coal combustion phenomena are presented.

An Examination Of The Relationships Among Learning Style, Attitudes, And Outcomes Of Computer-Assisted Instruction, Daniel Glen Wilson

Dissertations and Theses @ UNI

This research was based upon a hypothesized AptitudeTreatment Interaction (ATI). More specifically, the research investigated the relationships between student learning style (aptitude) and student outcomes with computer-assisted instruction (treatment). These outcomes included student achievement with computer-assisted instruction (CAI) and student attitude toward CAI.

To examine these relationships, a researcher-developed CAI program on light and color theory was validated and administered to 144 students in an educational media course at the University of Northern Iowa. Participants in the study were first asked to complete the Grasha-Riechmann Student Learning Style Scales (GRSLSS) inventory along with a demographic survey. Next, each participant completed …

The Characteristics Of Motion And Time Study In Taiwan's Electronics Industry And Their Relationship To Business Size, Betty Chang

Dissertations and Theses @ UNI

This research was conducted to investigate the characteristics of motion and time study implementation in Taiwan's electronics industry, as perceived by industrial engineers, and the relationships of these perceptions to business sizes of the firms. The questionnaires were mailed to 252 industrial engineers in the general firms group. A total of 206 (81.75%) instruments were returned. The questionnaires were then mailed to another 15 industrial engineers in the highly productive firms group. All the instruments (100%) were returned from the highly productive firm group. Telephone interviews were later conducted with six selected highly productive electronics firms to investigate their successful …

Threshold Characteristics Of Multimode Semiconductor Lasers, Lee W. Casperson, Mehdi Khoshnevissan

Electrical and Computer Engineering Faculty Publications and Presentations

The effects of spontaneous emission on the threshold characteristics of multimode laser oscillators with mixed line broadening are considered in detail. Most previous studies of multimode laser operation have emphasized the two limits of homogeneous and inhomogeneous broadening. With homogeneous broadening there is a tendency for oscillation in a single longitudinal mode, while in the inhomogeneous limit oscillation over much of the gain spectrum is expected. All practical lasers are somewhere between these limits, and this study explores the mode characteristics of lasers with mixed line broadening. Special attention is given to the important practical case of semiconductor diode lasers, …

Transform Method Of Processing For Speckle Strain-Rate Measurements, Donald D. Duncan, Sean J. Kirkpatrick, F. Fausten Mark, Lawrence W. Hunter

Electrical and Computer Engineering Faculty Publications and Presentations

We have developed a highly sensitive method for measuring thermal expansion, mechanical strain, and creep rates. We use the well-known technique of observing laser speckle with a pair of linear array cameras, but we employ a data-processing approach based on a two-dimensional transform of the speckle histories from each camera. This technique can effect large gauge sizes, which are important in the assessment of the spatial statistics of creep. Further, the algorithm provides simultaneous global estimates of the strain rates at both small- and large-scale sizes. This feature may be of value in the investigation of materials with different short- …

Programmable Analog Array Circuit, Marek Perkowski, Edmund Pierzchala

Electrical and Computer Engineering Faculty Publications and Presentations

There is disclosed a programmable analog or mixed analog/ digital circuit. More particularly, this invention provides a circuit architecture that is ?exible for a programmable electronic hardWare device or for an analog circuit Whose input and output signals are analog or multi-valued in nature, and primarily continuous in time. There is further disclosed a design for a current-mode integrator and sample-and-hold circuit, based upon Miller effect.

Fabrication Of 2-2 Connectivity Pzt/Thermoplastic Composites For High Frequency Linear Arrays, Wayne Huebner, Mary R. Reidmeyer, L. Busse, Jeffry W. Stevenson

Materials Science and Engineering Faculty Research & Creative Works

An alternate approach for fabricating PZT/polymer composites with 2-2 connectivity with fine scales is described. Thin (less than or equal to 20 micrometers) sintered PZT plates and sheets of a thermoplastic polymer film (less than or equal to 10 micrometers) were bonded together via thermal processing. Stack sintering of tape cast PZT generated the necessary PZT plates, while tape cast polymers were used to control the thermoplastic thickness. Composite blocks were cut to required dimensions for linear arrays, electroded, and poled. Electromechanical properties were measured to evaluate the composites. The significance of this fabrication technique is that it is able …

Longwall Electrical Control Issues: A Hazardous Waste Containment Application, D. Martinelli, R. S. Nutter Jr., R. Larry Grayson

Mining Engineering Faculty Research & Creative Works

No abstract provided.

Multigrid Acceleration Of Time-Dependent Solutions Of Navier-Stokes Equations, Sarafa Oladele Ibraheem

Mechanical & Aerospace Engineering Theses & Dissertations

Recent progress in Computational Fluid Dynamics is encouraging scientists to look at fine details of flow physics of problems in which natural unsteady phenomena have hitherto been neglected. The acceleration methods that have proven very successful in steady state computations can be explored for time dependent computations. In this work, an efficient multigrid methods is developed to solve the time-dependent Euler and Navier-Stokes equations. The Beam-Warming ADI method is used as the base algorithm for time stepping calculations. Application of the developed algorithm proved very efficient in selected steady and unsteady test problems. For instance, the inherent unsteadiness present in …

Modification Of Highway Soil Subgrades, Tommy C. Hopkins, Tony L. Beckham, David Q. Hunsucker

Kentucky Transportation Center Research Report

Major study objectives were to develop highway pavement subgrade stabilization guidelines, examine long-term benefits of chemical stabilizers, such as cement, hydrated lime, and two byproducts from industrial processes, and to establish a subgrade stabilization program in Kentucky. In developing a program, a number of design and construction issues had to be resolved. Factors affecting subgrade behavior are examined. Changes in moisture content and CBR strengths of untreated and chemically treated subgrades at three experimental highway routes were monitored over a 7- year period. CBR strengths of the untreated subgrades decreased dramatically while moisture contents increased. CBR strengths of subgrade sections …

Bs News

Building Services Engineering

No abstract provided.

A Frequency Domain Based Self-Tuning Pid Controller, John Ringwood, Aidan O'Dwyer

Conference papers

Traditionally, both explicit and implicit self-tuning controllers have employed time domain techniques for the identification and tracking of plant and controller parameters. The use of the frequency domain provides concise information on the dynamics of the process which has led to its wide acceptance as a domain for controller design. This paper demonstrates a method employing recursive, on-line measurement of the process frequency response, with a straightforward calculation of PID controller parameters. The computational effort involved is comparable with that of a time domain technique.

Model Parameter And Time Delay Estimation Using Gradient Methods, Aidan O'Dwyer, John Ringwood

Conference papers

A number of approaches have been proposed for parameter and time delay estimation of process models in single input, single output (SISO) control systems using gradient descent algorithms; some of these approaches involve the selection of a rational polynomial that is used to approximate time delay variations. This paper takes a generalised approach to the investigation of the most appropriate choice of the rational polynomial, and the gradient descent algorithm, to be used.

Using Statistics In Industry - Quality Improvement Through Total Process Control, Edward Sweeney, Gordon Betteley, Neville Mettrick, David Wilson

Books/Book chapters

No abstract provided.

An Expert System-Based Approach To Hospitality Company Diagnosis, Andrew Balfe, Peter O'Connor, Ciaran Mcdonnell

Conference papers

This paper describes the development of a prototype Expert System-based Analysis and Diagnostic (ESAD) package for the Hotel and Catering Industry. This computerised tool aids the hospitality manager in methodically scrutinising the hotel unit and environment, combining key information with systematic reasoning. The system searches through its extensive knowledge base, investigating complicated relationships. The number of possibilities considered is increased which will broaden the depth and breadth of the analysis and therefore should improve the quality of the managers decision making.

Characterization Of Phase Transformation Behavior In Electrolytically Produced Indium-Thallium Shape Memory Alloy Films, Chong Ho Sonu, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

Indium-thallium alloys in the range 15-38 at. % Tl were electrodeposited from a sulfate electrolyte by using pulsed current. The relationship between composition and phase structure of the alloys deposited was investigated with regard to the shape memory effect. To date there have been no reported experimental studies describing the electrodeposition of InTl alloys capable of undergoing such transformations. Not only did the deposited alloys exhibit the shape memory effect, but the composition-phase relationship exhibited was shown to deviate from that reported for alloys in an equilibrium condition. The results show that the temperature and the temperature interval for the …

A Modular Approach To Numerical Em Modeling, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

Discusses the components of numerical EM modelling codes. The authors go on to discuss a modular approach to EM software development which would allow developers to focus on one component at a time. The modular approach relies on standard format input and output files for each component (or module) of the code

A Study Of The Sintering Mechanism Of Pzt-Based Piezoceramics, Wayne Huebner, Pei Wen Lu, Wanrong Xue

Materials Science and Engineering Faculty Research & Creative Works

The densification behavior a PZT-based composition with additions of BiFeO3 as a flux was studied. Two different PZT powders were studied with varying initial particle sizes. Results clearly showed that BiFeO3 forms a low temperature liquid that aids in the densification behavior, with 3 mole% being optimum. Fine particle sizes substantially improved the density at low temperatures, with the net result that ceramics could be densified in air without the aid of a lead source. The corresponding electromechanical properties were typical of a hard PZT formulation.

Correlation Of Wettability And Interfacial Reaction To The Densification And Dielectric Properties Of Fluxed-Batio₃, Sea-Fue Wang, Wayne Huebner, Joseph P. Dougherty

Materials Science and Engineering Faculty Research & Creative Works

Reducing the sintering temperature of BaTiO3 has typically been achieved through the use of a fluxing agent to promote densification by liquid phase sintering. Liquid phase formation in these systems is due either to the melting of the flux or to the formation of a eutectic liquid between the flux and BaTiO3. In this paper, the correlation between the wettability and interfacial reactions between fluxes and BaTiO3 with respect to the densification behavior associated with liquid phase sintering, and the resulting dielectric properties is presented. Fluxes used in this study include 5ZnO*2B2O3, 5CdO*2SiO2, Pb5Ge3O11, CuO*TiO2, 3Bi2O3*B2O3, and LiF.

Processing And Characterization Of Samarium And Manganese Modified Lead Titanate Thin Film, Chen-Lung Fan, Wayne Huebner

Materials Science and Engineering Faculty Research & Creative Works

Samarium and manganese modified lead titanate thin films were fabricated by spin-coating an amorphous citrate precursor. These films transformed into an oxide film upon heat treatment at 400 degrees Celcius or above. Relatively large area and crack-free thin films could be obtained by this process both easily and inexpensively. The rheological behavior of the precursor solution, as well as its thermal decomposition and phase development were studied by means of DSC/TGA and XRD. The thickness and grain size of the oxide film were examined by TEM and SEM.

Positron Annihilation Determination Of Damage Caused By Fatigue Cycling In The Superalloy Haynes 188, D. Hoeckelman, Hollis P. Leighly

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Liquid-Mix Synthesis Of Oxide Powders And Thin Films Using A Starch-Based Polymer, Lone Wen F. Tai, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

A commercially available water-soluble starch derivative was used as the sole organic precursor in the Liquid-Mix synthesis of mixed-cation oxide powders and thin films. The acidified polymer (by nitric acid) was able to complex metal ions through the carboxylate ligands. Loosely agglomerated fine powders as well as dense thin films of complex oxides have been prepared using the same type of polymer. Oxide powders of Cr-doped lanthanum aluminate and yttrium aluminum garnet both crystallized in a single step, without forming any intermediate or second phases, when the amorphous resin intermediates were calcined at 650 °C and 750 °C for 2 …

Density Changes During Isothermal Annealing Of A Quenched Pb–7.45 At% Sn Alloy, Hollis P. Leighly, A. Belaidi

Materials Science and Engineering Faculty Research & Creative Works

The increase in density of a Pb–7.45 at% Sn alloy annealed at 150, 165, 180, and 195 °C and quenched at 20, 21.5, 23, 25, and 30 °C is measured isothermally. This increase in density accompanies the formation of the Sn‐rich phase precipitating as a function of time at the quenching temperature. The quenching is rapid enough to retain some vacancies at equilibrium at the annealing temperature. These vacancies accelerate the early stages of precipitation. The change in density versus time obeys the kinetic law allowing the determination of the reaction rate constant for several annealing and quenching conditions. Copyright …

Development Of Strength Theories For Random Fiber Composites, Victor Giurgiutiu

Faculty Publications

A ressessment of existing theories for calculating the strength of random and quasi-random fiber composites is presented. Fundamental aspects regarding the physical model, macromechanics analysis, fiber distribution functions, generalized failure criterion, and progressive versus sudden failure models are covered first. Progressive ductile failure, progressive brittle failure, and sudden brittle failure are treated in detail. In each case, the original theory is briefly reviewed, and then its extensions accompanied by numerical examples are presented. Several limitations originally imposed by Hahn, such as the monotonically nonincreasing requirement on the failure strain curve, are lifted and the mathematical formulations are generalized. Some common …

Efficacy Of Implementing An Ergonomics Program In An Industrial Setting Regarding Cumulative Trauma Disorders To The Upper Extremity, Christa Abraham, Lisa Evans, Patrick Hoban

Masters Theses

The purpose of this study was to determine if implementation of an industrial ergonomics program would decrease the number of upper extremity cumulative trauma disorders, lost days of work, and insurance costs. Data was collected from company records and OSHA logs including type of injury, lost days of work, restricted days of work, and insurance costs. This data was then analyzed using regression analysis and descriptive statistics.; The results of this study supported the concept that ergonomic programs may decrease the number of lost days of work. In this study, a number of limitations and weak correlations were found between …

The Components And Benefits Of An Advanced Surface Arterial Traffic Management System, Ted M. Andrews, Kumares C. Sinha

JTRP Technical Reports

Traffic congestion has become an increasing problem on major surface arterial roadways. Demand for accessibility to adjacent land uses yields increased vehicular turning movement activity at driveways and intersections. As turning and cross-road traffic volumes increase, the need for traffic signalization will eventually be warranted. When numerous, independently operating traffic signals are present on a given arterial roadway, adverse effects can result. First, continous movement along the arterials at a desirable speed may not be assured. Second, vehicular delay will increase because of the slower operating speeds and increased number of stops. Third, safety can be threatened as poor traffic …